comparing brands

[Sijray21]

you're beyond the point of having instructors so you can get away with it, but most instructors won't step inside a car rigged that way.

Says who? A good part of the HPDE crowd does this, and every instructor i've spoken with doesnt have a problem with it. I've instructed that way, and as long as the harness is properly mounted, with a rollbar - its fine. A seat is more better, of course but it wont stop anyone from getting in the car.

actually my last instructor (the same one Chris had) also said that he wouldn't step into a car for instruction if the driver was heavily secure and the passenger side had a seat-belt and 3-point. I think if you're going to place safety enhancements that the passenger should have additional protection (maybe not as nice, but equally or near equally as protective as the driver).

he would be "very hesitant" were his exact words. And depending on his driving he would or would not remain as the instructor.